Pro Bash Programming · Scripting the GNU/Linux Shell · 2nd Edition by Varma, Jayant -- Read -- Imperial Library of Trantor

Index

Cover Title Copyright Dedication Contents at a Glance Contents About the Authors Acknowledgments Chapter 1: Hello, World: Your First Shell Program

The Code The File

The Naming of Scripts Selecting a Directory for the Script Creating the File and Running the Script

Choosing and Using a Text Editor Building a Better “Hello, World!” Summary

Commands Concepts Variables

Exercises

Chapter 2: Input, Output, and Throughput

Parameter and Variables

Positional Parameters Special*@#0$?_!- Parameters Variables

Arguments and Options echo, and Why You Should Avoid It printf: Formatting and Printing Data

Escape Sequences Format Specifiers Width Specification Printing to a Variable

Line Continuation Standard Input /Output Streams and Redirection

Redirection: >, >>, and <

Reading Input Pipelines Command Substitution Summary

Commands Concepts

Exercises

Chapter 3: Looping and Branching

Exit Status Testing an Expression

test, a.k.a. [ … ] [[ … ]]: Evaluate an Expression (( … )): Evaluate an Arithmetic Expression

Conditional Execution

if Conditional Operators, & and || case

Looping

while until for break continue

Summary

Commands Concepts

Exercises

Chapter 4: Command-Line Parsing and Expansion

Quoting Brace Expansion Tilde Expansion Parameter and Variable Expansion Arithmetic Expansion Command Substitution Word Splitting Pathname Expansion Process Substitution Parsing Options Summary

Commands

Exercises

Chapter 5: Parameters and Variables

The Naming of Variables The Scope of a Variable: Can You See It from Here? Shell Variables Parameter Expansion

Bourne Shell POSIX Shell Bash Bash-4.0

Positional Parameters Arrays

Integer-Indexed Arrays Associative Arrays

Summary

Commands Concepts

Chapter 6: Shell Functions

Definition Syntax Compound Commands Getting Results

Set Different Exit Codes Print the Result Place Results in One or More Variables

Function Libraries

Using Functions from Libraries

Sample Script Summary

Commands

Exercises

Chapter 7: String Manipulation

Concatenation

Repeat Character to a Given Length

Processing Character by Character

Reversal

Case Conversion Comparing Contents Without Regard to Case Check for Valid Variable Name Insert One String into Another

Examples

Overlay

Examples

Trim Unwanted Characters

Examples

Index Summary

Commands Functions

Exercises

Chapter 8: File Operations and Commands

Reading a File External Commands

cat head touch ls cut wc

Regular Expressions

grep sed awk

File Name Expansion Options

nullglob failglob dotglob extglob nocaseglob globstar

Summary

Shell Options External Commands

Exercises

Chapter 9: Reserved Words and Built-In Commands

help, Display Information About Built-In Commands time, Print Time Taken for Execution of a Command read, Read a Line from an Input Stream

-r, Read Backslashes Literally -e, Get Input with the readline Library -a, Read Words into an Array -d DELIM, Read Until DELIM Instead of a Newline -n NUM, Read a Maximum of NUM Characters -s, Do Not Echo Input Coming from a Terminal -p PROMPT:, Output PROMPT Without a Trailing Newline -t TIMEOUT, Only Wait TIMEOUT Seconds for Complete Input -u FD: Read from File Descriptor FD Instead of the Standard Input -i TEXT, Use TEXT as the Initial Text for Readline eval, Expand Arguments and Execute Resulting Command Poor Man’s Arrays Setting Multiple Variables from One Command

type, Display Information About Commands builtin, Execute a Built-In Command command, Execute a Command or Display Information About Commands pwd, Print the Current Working Directory

unalias, Remove One or More Aliases

Deprecated Built-Ins Dynamically Loadable Built-Ins Summary

Commands and Reserved Words Deprecated Commands

Exercise

Chapter 10: Writing Bug-Free Scripts and Debugging the Rest

Prevention Is Better Than Cure

Structure Your Programs Document Your Code Format Your Code Consistently The K.I.S.S. Principle Test as You Go

Debugging a Script Summary Exercises

Chapter 11: Programming for the Command Line

Manipulating the Directory Stack

cd pd cdm menu

Filesystem Functions

l lsr cp, mv md

Miscellaneous Functions

pr1 calc

Managing Man Pages

sman sus k

Games

The fifteen Puzzle

Summary Exercises

Chapter 12: Runtime Configuration

Defining Variables Command-Line Options and Arguments Menus Q&A Dialogue Configuration Files Scripts with Several Names Environment Variables All Together Now

Script Information Default Configuration Screen Variables Function Definitions Parse Command-Line Options Bits and Pieces

Summary Exercises

Chapter 13: Data Processing

Arrays

Holes in an Indexed Array Using an Array for Sorting Two-Dimensional Grids

Data File Formats

Line-Based Records Block File Formats

Summary Exercises

Chapter 14: Scripting the Screen

Teletypewriter vs. Canvas Stretching the Canvas

Command Sequence Introducer

Priming the Canvas Moving the Cursor Changing Rendition Modes and Colors Placing a Block of Text on the Screen Scrolling Text Rolling Dice Summary Exercises

Chapter 15: Entry-Level Programming

Single-Key Entry

Function Library, key-funcs

History in Scripts Sanity Checking Form Entry Reading the Mouse Summary Exercises

Appendix A: Shell Variables

BASH BASHPID BASH_ALIASES BASH_ARGC BASH_ARGV BASH_CMDS BASH_COMMAND BASH_EXECUTION_STRING BASH_LINENO BASH_REMATCH BASH_SOURCE BASH_SUBSHELL BASH_VERSINFO BASH_VERSION COMP_CWORD COMP_KEY COMP_LINE COMP_POINT COMP_TYPE COMP_WORDBREAKS COMP_WORDS DIRSTACK EUID FUNCNAME GROUPS HISTCMD HOSTNAME HOSTTYPE LINENO MACHTYPE OLDPWD OPTARG OPTIND OSTYPE PIPESTATUS PPID PWD RANDOM REPLY SECONDS SHELLOPTS SHLVL UID BASH_ENV CDPATH COLUMNS COMPREPLY EMACS FCEDIT FIGNORE GLOBIGNORE HISTCONTROL HISTFILE HISTFILESIZE HISTIGNORE HISTSIZE HISTTIMEFORMAT HOME HOSTFILE IFS IGNOREEOF INPUTRC LANG LC_ALL LC_COLLATE LC_CTYPE LC_MESSAGES LC_NUMERIC LINES MAIL MAILCHECK MAILPATH OPTERR PATH POSIXLY_CORRECT PROMPT_COMMAND PROMPT_DIRTRIM PS1 PS2 PS3 PS4 SHELL TIMEFORMAT TMOUT TMPDIR auto_resume histchars

Index

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